Remova a barra final com .htaccess

<IfModule mod_rewrite.c>
    RewriteEngine On            
    RewriteBase /

    # where the magic is done !
    RewriteRule (.*)/$ $1 [R=301,L]

    RewriteCond %{REQUEST_FILENAME} !-d
    RewriteCond %{REQUEST_FILENAME} !-f         
    RewriteRule ^(.*)$ index.php?url=$1 [PT,L]
</IfModule>